Sulfamethoxazole Enhances Specific Enzymatic Activities under Aerobic Heterotrophic Conditions: A Metaproteomic Approach

The growing concern about antibiotic-resistant microorganisms
has
focused on the sludge from wastewater treatment plants (WWTPs) as
a potential hotspot for their development and spread. To this end,
it seems relevant to analyze the changes on the microbiota as a consequence
of the antibiotics that wastewater may contain. This study aims at
determining whether the presence of sulfamethoxazole (SMX), even in
relatively low concentrations, modifies the microbial activities and
the enzymatic expression of an activated sludge under aerobic heterotrophic
conditions. For that purpose, we applied a metaproteomic approach
in combination with genomic and transformation product analyses. SMX
was biotransformed, and the metabolite 2,4­(1H,3H)-pteridinedione-SMX (PtO-SMX) from the pterin-conjugation
pathway was detected at all concentrations tested. Metaproteomics
showed that SMX at 50–2000 μg/L slightly affected the
microbial community structure, which was confirmed by DNA metabarcoding.
Interestingly, an enhanced activity of the genus Corynebacterium and specifically of five enzymes involved in its central carbon
metabolism was found at increased SMX concentrations. Our results
suggest a role of Corynebacterium genus on SMX risks
mitigation in our bioreactors.